全文获取类型
收费全文 | 1735篇 |
免费 | 51篇 |
国内免费 | 182篇 |
出版年
2023年 | 2篇 |
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 8篇 |
2015年 | 22篇 |
2014年 | 43篇 |
2013年 | 45篇 |
2012年 | 35篇 |
2011年 | 42篇 |
2010年 | 28篇 |
2009年 | 85篇 |
2008年 | 99篇 |
2007年 | 89篇 |
2006年 | 89篇 |
2005年 | 69篇 |
2004年 | 60篇 |
2003年 | 72篇 |
2002年 | 48篇 |
2001年 | 60篇 |
2000年 | 55篇 |
1999年 | 98篇 |
1998年 | 72篇 |
1997年 | 63篇 |
1996年 | 66篇 |
1995年 | 66篇 |
1994年 | 58篇 |
1993年 | 57篇 |
1992年 | 38篇 |
1991年 | 43篇 |
1990年 | 36篇 |
1989年 | 54篇 |
1988年 | 22篇 |
1987年 | 41篇 |
1986年 | 41篇 |
1985年 | 28篇 |
1984年 | 41篇 |
1983年 | 8篇 |
1982年 | 29篇 |
1981年 | 22篇 |
1980年 | 23篇 |
1979年 | 14篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有1968条查询结果,搜索用时 31 毫秒
41.
基于醇溶蛋白的20份小麦种质遗传完整性分析 总被引:13,自引:3,他引:10
采用醇溶蛋白电泳技术对同一品种不同繁殖年份的20份小麦种质进行遗传完整性分析。结果表明:供试种质中有10份具有一种醇溶蛋白谱带带型的同质性种质;另外10份具有2~4种醇溶蛋白谱带带型的异质性种质,其中6份为地方品种。表明地方品种具有较高的遗传多样性。在10份异质性种质中,两个繁殖年份种质之间的醇溶蛋白带型频率变化差异不显著的有5份,其第一繁殖年份的种质发芽率均高于75%,而另外5份存在显著差异的种质,第一年份的发芽率都低于66%。进一步分析表明,这10份异质性种质在两个繁殖年份之间,其发芽率差值与带型频率差值之间呈极显著正相关,相关系数为0.8665。上速结果表明,小麦更新时较高的发芽率是维持异质性种质遗传完整性的关键因素。 相似文献
42.
中国小麦地方品种内和品种间醇溶蛋白遗传多样性分析 总被引:8,自引:0,他引:8
为了揭示中国小麦地方品种内遗传异质性和品种间的遗传多样性,采用A-PAGE方法,对72份来自不同生态区的地方品种进行醇溶蛋白构成分析。结果发现,全部供试地方品种共观察到101条迁移率不同的务带,构成229种醇溶蛋白构型,每个品种醇溶蛋白条带数目为14—24。63份(87.5%)地方品种在品种内具有2种以上醇溶蛋白变异类型,其中,变异类型最多的品种二红皮小麦(ZM004659)30个子粒中有14种之多,多数品种具有2—3种变异类型。品种内醇溶蛋白构型一致的品种共有9个,占12.5%。这表明供试的大多数小麦地方品种内个体间在醇溶蛋白构成上具有遗传异质性。聚类分析表明,相同生态区的地方品种没有整齐地聚为一类。 相似文献
43.
Qing-Shan Chang Rong-Hua Zhou Xiu-Ying Kong Zeng-Liang Yu Ji-Zeng Jia 《植物学报(英文版)》2006,48(11):1348-1354
Talgu Genlc Male Sterile Wheat (TGMSW; Trltlcum aestlvum L.), a dominant genic male sterile germplasm, is of considerable value in the genetic Improvement of wheat because of Its stable Inherence, complete male abortion, and high cross-fertilization rate. To Identify specially transcribed genes In sterile anther, a suppression subtractlve hybridization (aSH) library was constructed with sterile anther as the tester and fertile anther as the driver. A total of 2 304 SSH Inserts amplified by polymerase chain reaction were arrayed using robotic printing. The cDNA arrays were hybridized with 32P-labeled probes prepared from the RNA of forward- and reverse-subtracted anthers. Ninety-six clones were scored as upregulated in sterile anthers compared with the corresponding fertile anthers and some clones were selected for sequencing and analysis In GenBank. Based on their putative functions, 87 non-redundant clones were classified Into the following groups: (i) eight genes Involved In metabolic processes; (11) four material transportation genes; (iii) three signal transductlon-assoclated genes; (iv) four stress response and senescence-associated protein genes; (v) seven other functional protein genes; (vi) five genes with no known function; and (vii) another 56 genes with no match to the databases. To test the hybridization efficiency, eight genes were selected and analyzed by Northern blot. The results of the present study provide a comprehensive overview of the genes and gene products Involved In anther abortion In TGMSW. 相似文献
44.
Genetic Diversity and Core Collection Evaluations in Common Wheat Germplasm from the Northwestern Spring Wheat Region in China 总被引:6,自引:0,他引:6
C. Y. Hao X. Y. Zhang L. F. Wang Y. S. Dong X. W. Shang J. Z. Jia 《Molecular breeding : new strategies in plant improvement》2006,17(1):69-77
Fluorescence microsatellite markers were employed to reveal genetic diversity of 340 wheat accessions consisting of 229 landraces
and 111 modern varieties from the Northwest Spring Wheat Region in China. The 340 accessions were chosen as candidate core
collections for wheat germplasm in this region. A core collection representing the genetic diversity of these accessions was
identified based on a cluster dendrogram of 78 SSR loci. A total of 967 alleles were detected with a mean of 13.6 alleles
(5–32) per locus. Mean PIC was 0.64, ranged from 0.05 to 0.91. All loci were distributed relatively evenly in the A, B and
D wheat genomes. Mean genetic richness of A, B and D genomes for both landraces and modern varieties was B > A > D. However,
mean genetic diversity indices of landraces changed to B > D > A. As a whole, genetic diversity of the landraces was considerably
higher than that of the modern varieties. The big difference of genetic diversity indices in the three genomes suggested that
breeding has exerted greater selection pressure in the D than the A or B genomes in this region. Changes of allelic proportions
represented in the proposed core collection at different sampling scales suggested that the sampling percentage of the core
collection in the Northwest Spring Wheat Region should be greater than 4% of the base collection to ensure that more than
70% of the variation is represented by the core collection.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
45.
46.
47.
《Archives of animal nutrition》2013,67(4):381-390
Four fungi varieties (Wild variety, Chaetomium cellulolyticum, Trichoderma harzianum and Penicillium colony 10) were cultivated in a solid‐state fermentation on a wheat straw‐wheat bran‐sugar beet pulp mixture (20 : 40: 40%). The fermented substrates contained xylanase (22.1 to 78.6 Units g‐1 DM) and cellulase (0.47 to 14.0 Units g‐1 DM). Fermented substrate was homogeneously mixed with ground wheat straw (1: 2; 1: 5 and 1 : 10), moistened to 30 or 50% DM, airtightly stored for 24 h at 50°C and deep frozen. All samples were given in nylon bags and incubated for 48 h in the rumen of 4 sheep. In sacco DMD decreased with higher straw proportions in the mixture (1: 2; 1 : 5 and 1: 10: 52.0; 46.8 and 44.2% resp.), the DM‐content did not significantly influence the in sacco DMD. The Wild variety and Chaetomium cellulolyticum did not significantly influence the in sacco DMD, Trichoderma harzianum and Penicillium colony 10 decreased DMD in some cases. In general added fungi did not improve the rumen degradability of fibre. 相似文献
48.
K Matthäus S Dänicke W Vahjen O Simon J Wang H Valenta 《Archives of animal nutrition》2013,67(1):19-35
The objective of this study was to follow the mycotoxin formation and changes in nutrient composition of wheat (cv. Ritmo) artificially inoculated with Fusarium culmorum. From anthesis until harvest, samples were taken once a week from the inoculated and control plots. The investigations were focused on monitoring the progression of the contamination of the wheat kernels with deoxynivalenol (DON) and zearalenone (ZON). Both the uncontaminated control kernels and the contaminated kernels were examined also for the presence of zearalenone-4-beta-D-glucopyranoside and several trichothecenes at harvest. Furthermore, the impact of the Fusarium inoculation on some nutrients as starch, crude protein, amino acid composition, crude ash, non starch polysaccharides (NSP) as well as viscosity and thousand seed weight (TSW) was examined. Also proteolytic and amylolytic activity as well as the NSP-degrading enzyme activities of inoculated and control samples were analysed at the time of harvest. DON was detected in higher concentrations and in earlier stages, while ZON was found later and in smaller amounts. On average 7.79?mg/kg DM of DON and 100?μg/kg DM of ZON were found in the inoculated kernels at the time of harvest. Neither in the contaminated nor in the control samples glucose conjugates of ZON (Zearalenone-4-beta-D-glucopyranoside) were detected. Moreover, the infection with Fusarium culmorum had pronounced effects on some quality parameters. The crude protein content of the inoculated kernels showed significantly higher values over the whole period compared to the control kernels. The protein content of the inoculated kernels amounted 13.9% DM at harvest, while only a concentration of 12.5% DM was detected in the control samples. Similarly, in almost all stages of development the crude ash content of inoculated samples was higher than in control samples. These distinct differences in kernel composition resulted possibly from the changes of the thousand seed weight. In the present work the grain harvested from the control plots showed a significantly higher TSW (24.2?g) as compared to their inoculated counterparts (15.5?g). Despite lower extract viscosity of inoculated samples at time of harvest, the content of soluble NSP of inoculated plots was higher than in control samples at the same time. Moreover, inoculation resulted in markedly increased activities of protease, amylase and several NSP-degrading enzyme activities. This would suggest that the cell wall penetrating properties of the fungus itself and/or that the fungus induced alterations of the metabolic activity of the embryo or other constituents of the wheat kernel could be responsible. 相似文献
49.
Recently, Mucor indicus was introduced as a promising ethanol producing microorganism for fermentation of lignocellulosic hydrolysates, showing a number of advantages over Saccharomyces cerevisiae. However, high nutrient requirement is the main drawback of the fungus in efficient ethanol production from lignocelluloses. In this study, application of fungal extract as a potential nutrient source replacing all required nutrients in fermentation of wheat straw by M. indicus was investigated. Wheat straw was pretreated with N-methylmorpholine-N-oxide (NMMO) at 120 °C for 1–5 h prior to enzymatic hydrolysis. Hydrolysis yield was improved at least by 6-fold for 3 h pretreated straw compared with that of untreated one. A fungal extract was produced by autolysis of M. indicus biomass, an unavoidable byproduct of fermentation. Maximum free amino nitrogen (2.04 g/L), phosphorus (1.50 g/L), and total nitrogen (4.47 g/L) as well as potassium, magnesium, and calcium in the fungal extract were obtained by autolysis of the biomass at 50 °C and pH 5.0. The fungal extract as a nutrient-rich supplement substituted yeast extract and all other required minerals in fermentation and enhanced the ethanol yield up to 92.1% of the theoretical yield. Besides, appreciate amounts of chitosan were produced as another valuable product of the autolysis. 相似文献
50.
Effect of lead stress on mineral content and growth of wheat (Triticum aestivum) and spinach (Spinacia oleracea) seedlings 总被引:1,自引:0,他引:1
Mostafa Lamhamdi Ouiam El Galiou Ahmed Bakrim Juan Carlos Nóvoa-Muñoz Manuel Arias-Estévez Ahmed Aarab René Lafont 《Saudi Journal of Biological Sciences》2013,20(1):29-36
Lead (Pb) is the most common heavy metal contaminant in the environment. Pb is not an essential element for plants, but they absorb it when it is present in their environment, especially in rural areas when the soil is polluted by automotive exhaust and in fields contaminated with fertilizers containing heavy metal impurities. To investigate lead effects on nutrient uptake and metabolism, two plant species, spinach (Spinacia oleracea) and wheat (Triticum aestivum), were grown under hydroponic conditions and stressed with lead nitrate, Pb(NO3)2, at three concentrations (1.5, 3, and 15 mM).Lead is accumulated in a dose-dependent manner in both plant species, which results in reduced growth and lower uptake of all mineral ions tested. Total amounts and concentrations of most mineral ions (Na, K, Ca, P, Mg, Fe, Cu and Zn) are reduced, although Mn concentrations are increased, as its uptake is reduced less relative to the whole plant’s growth. The deficiency of mineral nutrients correlates in a strong decrease in the contents of chlorophylls a and b and proline in both species, but these effects are less pronounced in spinach than in wheat. By contrast, the effects of lead on soluble proteins differ between species; they are reduced in wheat at all lead concentrations, whereas they are increased in spinach, where their value peaks at 3 mM Pb.The relative lead uptake by spinach and wheat, and the different susceptibility of these two species to lead treatment are discussed. 相似文献